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Effect of Addition of Polyphosphates and Salt Before and After Cooking on Quality of Freeze-Dried Cooked Chicken
Effect of Addition of Polyphosphates and Salt Before and After Cooking on Quality of Freeze-Dried Cooked Chicken A. A. KLOSE, B. G. LYON, and W. D. DAY
Animal Products Composition and Utilization Research Unit, United States Department of Agriculture, Science and Education Administration, Federal Research, Richard B. Russell Agricultural Research Center, Athens, Georgia 30604 (Received for publication March 30, 1978)
INTRODUCTION Freeze-dried, cooked, diced chicken is a product of definite, but limited, commercial and military interest because it is more costly and less palatable than freshly cooked chicken. Limitations in quality involve mainly the composite of textural properties, including rehydration capacity, juiciness, tenderness, and cohesiveness. Research over the past 20 years (Tappel et al, 1957; Tuomy and Felder, 1964; Bele et al, 1966) has defined these limitations and provided some processing modifications for improvement in quality. A recent study (Townsend et al, 1978) indicated that poor rehydration capacity and related quality loss of freezedried cooked chicken are little if at all influenced by excessive storage temperature and times, but are largely brought about by the processing and freeze-drying treatments. Shults et al. (1972) and Hinnergardt et al. (1975) demonstrated the beneficial effects of additions of polyphosphates and salt to beef on cooking shrink, and on tenderness, juiciness, and rehydration in freeze-dried, rehydrated beef steaks. Sharma and Seltzer (1977) found that incorporation of .35 to .50% Kena, 1.25 to 1.50% sodium chloride, and .15% wheat gluten into
1
Mention of commercial products does not imply recommendations over others not named. 1978 Poultry Sci 57:1573-1578
meat patties improved their texture, overall acceptability, and storage stability. As an extension of the work of Townsend et al. (1978) on chicken, we undertook to determine the effects of polyphosphate (Kena) and sodium chloride additions to broiler breast meat before and after cooking on the extent of rehydration and selected sensory properties of the rehydrated freeze-dried meat. EXPERIMENTAL PROCEDURE Experiment A. Two-hundred eviscerated and washed broilers, average weight 1.15 kg, were removed from a commercial processing line just before they were to enter the chiller and were transported in ice to the laboratory. Three hours post mortem the breast meat (Pectoralis major and minor) was cut free of skin from the chilled carcasses and divided into two equal lots, designated 1 and 2. Lot 1 was soaked at 3 C in water and lot 2 in a solution containing 3% Kena 1 plus 4% sodium chloride, both in stainless steel tanks, in ratio of .96 liter of solution (or water) per kg of meat. Levels of Kena and sodium chloride in the soaking solutions were selected on the basis of prior experience and extensive literature on the subject to provide an effective, but not unpalatable level. Levels in Experiment B were changed from those in Experiment A to more nearly approach the optimum in effectiveness and taste. After 3 hr, the
1573
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ABSTRACT Two processing experiments were run to evaluate the effects of polyphosphates (Kena) and sodium chloride added to broiler breast meat on the yields, rehydration capacity, and sensory quality of the freeze-dried cooked, diced meat. In Experiment A, early post mortem breast meat was treated with a solution of 3% Kena-4% sodium chloride either before cooking, after cooking, or both. In Experiment B, chilled, aged breast meat was treated with 2% sodium chloride, 3% Kena, or both before cooking and freeze-drying. In Experiment A, polyphosphate-salt treatment increased water uptake, cooked yield, and final rehydrated weight, and increased sensory qualities of juiciness, tenderness, and saltiness. For a single treatment, its application after cooking was as effective as that before cooking. For Experiment B, the same effects were observed, the 3% Kena producing the major impact and the 2% sodium chloride having small additional effects. Polyphosphate (Kena) treatment improved the eating quality of the freeze-dried product.
1574
KLOSE ET AL. phorus and chloride contents of the freezedried samples were determined by AOAC methods (AOAC, 1975). For sensory evaluation, 100 g of freeze-dried meat from each of the four sub-lots was added to about 750 ml of boiling distilled water and simmered for 20 min. The meat was then drained on a sieve for 5 min, weighed, and submitted in 18-g test portions to a trained panel of 10 members. The samples were scored for intensity of juiciness, tenderness, and saltiness on scales of 1 (very dry, tough, or bland) to 6 (very juicy, tender, or salty). All four sub-lots were scored at each of six replicated sessions. Rehydration and panel data were analyzed by analysis of variance. For brevity and clarity, the four sub-lots will be referred to in the Results section in terms of the sequence of treatments: water-air, water-salts, salts-air, salts-salts. Experiment B. About 90 kg of ice-packed broiler breasts with skin were obtained from commercial, conventionally processed, and water-chilled parts-missing broilers. Skins were removed about 18 to 20 hr post mortem, and four accurately weighed 18-kg portions of the skinless breasts were soaked at 3 C for 6 hr in the four solutions, respectively: 1) 20 liters of distilled water; 2) 20 liters of 2% sodium chloride; 3) 20 liters of 3% Kena; and 4) 20 liters of 2% sodium chloride, 3% Kena. The four lots were drained, held at 3 C for about 14 hr (overnight), weighed, and cooked in 88 C water con-
TABLE 1.—Effects of phosphate-salt treatment before and after cooking on water absorption, cooked yields, and rehydration capacity of freeze-dried chicken Experiment A Weight (% of raw) after treatment Treatment
Lot 1
Lot 2
None (raw) 3 hr in water or salts* Cooking
100.0 103.5 (water) 74.1
100.0 111.4 (salts)* 86.8 Sub-lots
3 hr in air or salt* Freeze-drying and rehydration Rehydration ratio**
la
lb
2a
2b
72.7 (air) 67.5 2.81 a
77.2 (salts)* 73.3 3.05 b
85.4 (air) 72.5 3.02°
90.6 (salts)* 76.5 3.18 c
•4% NaCl, 3% Kena. "Rehydrated weight divided by freeze-dried weight. Standard error .035. Different superscripts indicate significant difference at the 5% level.
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meat was drained and held unpackaged at 3 C in air overnight. Meat was then cooked in 89 C water (about 5 liters of water per kg of meat) to an internal temperature of 77 C, drained, and chilled in 3 C air for 2 hr. Each lot was then divided into two equal sublots: l a and l b , and 2a and 2b. The a's were chilled unpackaged in 3 C air 3 hr, and the b's in a 3 C solution containing 3% Kena and 4% sodium chloride for 3 hr. The four sub-lots were then chilled overnight to —3 C, diced to dimensions of 1.27 X 1.27 X .95 cm, frozen on trays in the available —23 C air blast, and freeze dried in a VacU-Dyne (Model VPFD-CX) 1 pilot-size freeze dryer. Pressure attained by vacuum pump was 250 microns; condenser temperature, about —45 C; and platen temperature, 49 C. Vacuum was released with high purity nitrogen. The dry product was packed under nitrogen in No. 2V4 tin cans and stored at —34 C. Determinations were made of yields, and of moisture contents by AOAC methods. For determination of rehydration capacity, about 20 g of accurately weighed, freeze-dried material was soaked in 150 ml of 80 C distilled water for 20 min, drained for 5 min, and weighed. Five replications were made per treatment. A rough measure of water-holding capacity was obtained from the volume of liquid expressed from the rehydrated samples by a 500-kg In^ stron-activated force acting through a 105 cm 2 plunger on about 20 g of sample. Phos-
POLYPHOSPHATES IN FREEZE-DRIED CHICKEN
1575
TABLE 2.-Minerals in freeze -dried meat. Experiment A* Sub-lot Successive treatments %Ash % Chloride, as NaCl % Phosphorus
la Water Air
lb Water Salts*
2a Salts* Air
2b Salts* Salts*
3.2 a
6.3b 2.1= .85 b
S.9b 1.2 b .97=
9.1= 3.9 d 1.08 d
.11
.73 a
•4% NaCl, 3% Kena. a, >c>dDifferent superscripts within rows indicate significant difference at 5% level. Means for duplicate determinations on dry basis; standard errors, from pooled variance, were .1 for ash, .1 for sodium chloride, and .003 for phosphorus.
Determinations of yields, moisture contents, phosphorus and chloride contents, rehydration capacities, and sensory evaluations were carried out as described above for Experiment A; however, there were only four replications of the sensory comparisons with seven panelists, and no compression tests by Instron were run.
RESULTS AND DISCUSSION Experiment A. Table 1 summarizes the effects of phosphate-salt treatments prior to and after cooking on water absorption, cooked yields, and rehydration capacity of the freezedried products. Water absorption of chicken breasts soaked in a solution of polyphosphates (Kena) with sodium chloride was more than twice that of breasts' soaked in water and cooked yield (based on original raw unsoaked weight) was increased 13% by the polyphosphate-salt treatment. Polyphosphate-salt treatment of sub-lots l b and 2b increased yield only about 5%. The final rehydrated yields ranged from 67% for the water-air control to 76% for the twice-soaked (salts-salts) sub-lot. These differences corresponded to 4% more moisture in the salts-salts rehydrated product than in the water-air control, i.e., 68.7% versus 64.5% (as calculated from the rehydration ratios and the moisture contents of the freeze-dried products). Hinnergardt et al. (1975) obtained a 6% difference in moisture content by phosphate-salt
TABLE 3.—Sensory scores of rehydrated freeze-dried meat. Experiment A Mean scores* Sublot la lb 2a 2b
Treatment
Juiciness
Tenderness
Saltiness
Water/air Water/salts** Salts/air Salts/salts
2.80 a 3.93°= 3.70b 4.47 c
2.48 a 4.42 c 3.73b 4.92 d
1.87 a 3.70b 3.28b 4.53=
'Means for 10 panelists and 6 replications, 1 = very dry or tough or bland; 6 = very juicy or tender or salty. **4%NaCl, 3% Kena. a,b,cr Different superscripts in columns indicate significant difference at 5% level.
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taining 1% sodium chloride to an internal meat temperature of 77 C. The cooked meat was drained, chilled t o —3 C overnight, machinediced to 1.27 X 1.27 X .95 cm size, frozen on trays in the available —34 C air blast, and freeze-dried in a Vac-U-Dyne pilot freeze-dryer (Model VPFD-CX). Pressure attained by vacuum pump was 500 microns; condenser temperature, about —45 C; and platen temperature, about 37 C. The reduction of platen temperature from that used in Experiment A was made to minimize heat damage. Freeze-drying required about 48 hr. Vacuum was released with nitrogen, and the dried product stored in desiccators under nitrogen at —34 C prior to evaluation.
3.20*
100.0 103.1 (2% NaCl) 72.7 71.0
Lot 2
3.35 b
100.0 120.6 (3% 93.8 77.6
Lot 3
Weight (% raw) after treat
(2% NaCl) 3.6° .65° .60*
(Water)
2.7 a .08 a .59 a
Means for duplicate determinations on dry basis; standard errors, from pooled variance, were .1 for ash, .08 fo ent superscripts within rows indicate significant difference at 5% level.
%Ash % Chloride, as NaCl % Phosphorus
Lot 2
Lot 1
TABLE 5.—Minerals in freeze-dried meat. Experiment B
•Rehydrated weight divided by freeze-dried weight. Standard error .04. Different superscripts indicate significant dif
3.17 a
100.0 99.0 (water) 68.6 68.5
None (raw) 6 hr in water or solution Cooking Freeze-drying and rehydration
Rehydration ratio*
Lot 1
of phospbate-salt treatments on water absorption, cooked yields, and r of freeze-dried chicken. Experiment B
Treatment
TABLE 4.—Effects
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TABLE 6.—Sensory scores of rehydrated freeze-dried meat. Experiment B Mean scores* Lot
Treatment
Juiciness
Tenderness
Saltiness
Water 2% NaCl 3% Kena 2% NaCl, 3% Kena
2.46 a 2.54a 4.1lb 4.32b
2.64a 2.86a 4.64b 4.68b
2.36 a 2.82 a b 3.29b 4.04=
*Mean for four replications, 7 panelists. 1 = Very dry or tough or bland; 6 = very juicy or tender or salty. a,b,c,Different superscripts in columns indicate significant difference at 5% level.
hydrated freeze-dried products, yield of the salt-Kena lot was 17% greater than that of the control. The rehydration ratio was significantly higher in lots 3 and 4 (Kena) than in lots 1 and 2, for tests with 20-g portions. Similar results were obtained with 100-g portions. Table 5 summarizes the data on mineral content. If we assume that the phosphate in the ash is in the ortho form, i.e., with phosphorus content around 22%, then increases in ash content can be accounted for essentially by combined increases in chloride (NaCl) and phosphate (Na 2 HP0 4 ). Sensory data (Table 6) showed that lots 3 and 4 were significantly more juicy and tender than 1 and 2. The saltiness of the salt plus Kena-treated lot was more intense than that of all others, and Kena alone significantly increased saltiness. However, all four lots received a small, probably slight, increment of saltiness from the cooking water which contained 1% sodium chloride. Results of these tests indicate that the quality of freeze-dried cooked chicken would be improved significantly by polyphosphates (Kena) and slightly more by both Kena and sodium chloride. There does not appear to be any advantage in applying polyphosphates before cooking in the early post mortem period compared to applying after cooking. Increases in rehydration capacity due to polyphosphate treatment were small but significant. While applications in these tests were made by soaking, commercial incorporation of polyphosphates and salt might better be made by injection. REFERENCES Association of Official Agricultural Chemists. 1975. Page 417—418 in Official methods of analysis of
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treatment in freeze drying beef, i.e., 56% versus 50%. Our values for the rehydration ratio, determined with five 20-g portions, were all significantly different from one another except for l b and 2a. Rehydration ratios obtained from the 100-g portions used in the sensory tests were lower than those in Table 1, ranging from 2.56 to 2.81; but the order of the sub-lots with respect to the amounts of water they took up was the same for both portion sizes. Probably there was greater loss of fine material through the sieves when the larger portions were handled. Table 2 provides some mineral contents of the four sub-lots. Increases in ash content corresponded roughly to increases in chloride and phosphorus. On a rehydrated weight basis, the salts-salts samples had .45% equivalent Kena (of 25.7% phosphorus content), based on the increment of phosphorus over the water-air control. On rehydrated weight basis, the salts-salts samples contained 1.3% more sodium chloride than the water-air control. The sensory panel data (Table 3) showed consistent increases in juiciness, tenderness, and saltiness in the order of sub-lots la, 2a, l b , and 2b; but not all differences were statistically significant at the 5% level. Compression tests on the rehydrated samples showed about 5% less liquid loss from the three Kena-treated sub-lots than from the water-air control (20% vs 25%). Experiment B. Table 4 summarizes the effects of polyphosphate and salt treatments on water absorption, cooked yields, and rehydration capacity of the freeze-dried products. The substantial gains in water absorption due to Kena were reflected in even larger gains, percentage-wise, in cooked yield. In the final re-
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AOAC. 12th ed. Bele, L. M., H. H. Palmer, A. A. Klose, and T. F. Irmiter, 1966. Evaluation of objective methods of measuring differences in texture of freeze-dried chicken meat. J. Food Sci. 31:791-800. Hinnergardt, L. C , S. R. Drake, and R. A. Kluter, 1975. Grilled freeze-dried steaks. Effects of mechanical tenderization plus phosphate and salt. J. Food Sci. 40:621-623. Sharma, S. C , and E. Seltzer, 1977. Development of procedures to minimize mechanical damage in freeze-dried meat patties. J. Food Sci. 42:1336— 1343. Shults, G. W., D. R. Russell, and E. Wierbicki, 1972. Effect of condensed phosphates on pH, swelling
and water-holding capacity of beef. J. Food Sci. 37:860-864. Tappel, A. L., R. Martin, and E. Plocher, 1957. Freeze-dried meat. V. Preparation, properties, and storage stability of precooked freeze-dried meats, poultry, and sea foods. Food Technol. 11:599— 603. Townsend, W. E., A. A. Klose, and B. G. Lyon, 1978. Chemical and sensory changes in freeze-dried chicken and pork during high temperature, oxygen-free storage. J. Food Sci. 43:1—5. Tuomy, J. M., and J. Felder, 1964. Effect of processing temperatures and cooking methods on the quality of freeze-dried cooked pork. Food Technol. 18:1959-1960.
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Animal Products Composition and Utilization Research Unit, United States Department of Agriculture, Science and Education Administration, Federal Research, Richard B. Russell Agricultural Research Center, Athens, Georgia 30604 (Received for publication March 30, 1978)
INTRODUCTION Freeze-dried, cooked, diced chicken is a product of definite, but limited, commercial and military interest because it is more costly and less palatable than freshly cooked chicken. Limitations in quality involve mainly the composite of textural properties, including rehydration capacity, juiciness, tenderness, and cohesiveness. Research over the past 20 years (Tappel et al, 1957; Tuomy and Felder, 1964; Bele et al, 1966) has defined these limitations and provided some processing modifications for improvement in quality. A recent study (Townsend et al, 1978) indicated that poor rehydration capacity and related quality loss of freezedried cooked chicken are little if at all influenced by excessive storage temperature and times, but are largely brought about by the processing and freeze-drying treatments. Shults et al. (1972) and Hinnergardt et al. (1975) demonstrated the beneficial effects of additions of polyphosphates and salt to beef on cooking shrink, and on tenderness, juiciness, and rehydration in freeze-dried, rehydrated beef steaks. Sharma and Seltzer (1977) found that incorporation of .35 to .50% Kena, 1.25 to 1.50% sodium chloride, and .15% wheat gluten into
1
Mention of commercial products does not imply recommendations over others not named. 1978 Poultry Sci 57:1573-1578
meat patties improved their texture, overall acceptability, and storage stability. As an extension of the work of Townsend et al. (1978) on chicken, we undertook to determine the effects of polyphosphate (Kena) and sodium chloride additions to broiler breast meat before and after cooking on the extent of rehydration and selected sensory properties of the rehydrated freeze-dried meat. EXPERIMENTAL PROCEDURE Experiment A. Two-hundred eviscerated and washed broilers, average weight 1.15 kg, were removed from a commercial processing line just before they were to enter the chiller and were transported in ice to the laboratory. Three hours post mortem the breast meat (Pectoralis major and minor) was cut free of skin from the chilled carcasses and divided into two equal lots, designated 1 and 2. Lot 1 was soaked at 3 C in water and lot 2 in a solution containing 3% Kena 1 plus 4% sodium chloride, both in stainless steel tanks, in ratio of .96 liter of solution (or water) per kg of meat. Levels of Kena and sodium chloride in the soaking solutions were selected on the basis of prior experience and extensive literature on the subject to provide an effective, but not unpalatable level. Levels in Experiment B were changed from those in Experiment A to more nearly approach the optimum in effectiveness and taste. After 3 hr, the
1573
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ABSTRACT Two processing experiments were run to evaluate the effects of polyphosphates (Kena) and sodium chloride added to broiler breast meat on the yields, rehydration capacity, and sensory quality of the freeze-dried cooked, diced meat. In Experiment A, early post mortem breast meat was treated with a solution of 3% Kena-4% sodium chloride either before cooking, after cooking, or both. In Experiment B, chilled, aged breast meat was treated with 2% sodium chloride, 3% Kena, or both before cooking and freeze-drying. In Experiment A, polyphosphate-salt treatment increased water uptake, cooked yield, and final rehydrated weight, and increased sensory qualities of juiciness, tenderness, and saltiness. For a single treatment, its application after cooking was as effective as that before cooking. For Experiment B, the same effects were observed, the 3% Kena producing the major impact and the 2% sodium chloride having small additional effects. Polyphosphate (Kena) treatment improved the eating quality of the freeze-dried product.
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KLOSE ET AL. phorus and chloride contents of the freezedried samples were determined by AOAC methods (AOAC, 1975). For sensory evaluation, 100 g of freeze-dried meat from each of the four sub-lots was added to about 750 ml of boiling distilled water and simmered for 20 min. The meat was then drained on a sieve for 5 min, weighed, and submitted in 18-g test portions to a trained panel of 10 members. The samples were scored for intensity of juiciness, tenderness, and saltiness on scales of 1 (very dry, tough, or bland) to 6 (very juicy, tender, or salty). All four sub-lots were scored at each of six replicated sessions. Rehydration and panel data were analyzed by analysis of variance. For brevity and clarity, the four sub-lots will be referred to in the Results section in terms of the sequence of treatments: water-air, water-salts, salts-air, salts-salts. Experiment B. About 90 kg of ice-packed broiler breasts with skin were obtained from commercial, conventionally processed, and water-chilled parts-missing broilers. Skins were removed about 18 to 20 hr post mortem, and four accurately weighed 18-kg portions of the skinless breasts were soaked at 3 C for 6 hr in the four solutions, respectively: 1) 20 liters of distilled water; 2) 20 liters of 2% sodium chloride; 3) 20 liters of 3% Kena; and 4) 20 liters of 2% sodium chloride, 3% Kena. The four lots were drained, held at 3 C for about 14 hr (overnight), weighed, and cooked in 88 C water con-
TABLE 1.—Effects of phosphate-salt treatment before and after cooking on water absorption, cooked yields, and rehydration capacity of freeze-dried chicken Experiment A Weight (% of raw) after treatment Treatment
Lot 1
Lot 2
None (raw) 3 hr in water or salts* Cooking
100.0 103.5 (water) 74.1
100.0 111.4 (salts)* 86.8 Sub-lots
3 hr in air or salt* Freeze-drying and rehydration Rehydration ratio**
la
lb
2a
2b
72.7 (air) 67.5 2.81 a
77.2 (salts)* 73.3 3.05 b
85.4 (air) 72.5 3.02°
90.6 (salts)* 76.5 3.18 c
•4% NaCl, 3% Kena. "Rehydrated weight divided by freeze-dried weight. Standard error .035. Different superscripts indicate significant difference at the 5% level.
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meat was drained and held unpackaged at 3 C in air overnight. Meat was then cooked in 89 C water (about 5 liters of water per kg of meat) to an internal temperature of 77 C, drained, and chilled in 3 C air for 2 hr. Each lot was then divided into two equal sublots: l a and l b , and 2a and 2b. The a's were chilled unpackaged in 3 C air 3 hr, and the b's in a 3 C solution containing 3% Kena and 4% sodium chloride for 3 hr. The four sub-lots were then chilled overnight to —3 C, diced to dimensions of 1.27 X 1.27 X .95 cm, frozen on trays in the available —23 C air blast, and freeze dried in a VacU-Dyne (Model VPFD-CX) 1 pilot-size freeze dryer. Pressure attained by vacuum pump was 250 microns; condenser temperature, about —45 C; and platen temperature, 49 C. Vacuum was released with high purity nitrogen. The dry product was packed under nitrogen in No. 2V4 tin cans and stored at —34 C. Determinations were made of yields, and of moisture contents by AOAC methods. For determination of rehydration capacity, about 20 g of accurately weighed, freeze-dried material was soaked in 150 ml of 80 C distilled water for 20 min, drained for 5 min, and weighed. Five replications were made per treatment. A rough measure of water-holding capacity was obtained from the volume of liquid expressed from the rehydrated samples by a 500-kg In^ stron-activated force acting through a 105 cm 2 plunger on about 20 g of sample. Phos-
POLYPHOSPHATES IN FREEZE-DRIED CHICKEN
1575
TABLE 2.-Minerals in freeze -dried meat. Experiment A* Sub-lot Successive treatments %Ash % Chloride, as NaCl % Phosphorus
la Water Air
lb Water Salts*
2a Salts* Air
2b Salts* Salts*
3.2 a
6.3b 2.1= .85 b
S.9b 1.2 b .97=
9.1= 3.9 d 1.08 d
.11
.73 a
•4% NaCl, 3% Kena. a, >c>dDifferent superscripts within rows indicate significant difference at 5% level. Means for duplicate determinations on dry basis; standard errors, from pooled variance, were .1 for ash, .1 for sodium chloride, and .003 for phosphorus.
Determinations of yields, moisture contents, phosphorus and chloride contents, rehydration capacities, and sensory evaluations were carried out as described above for Experiment A; however, there were only four replications of the sensory comparisons with seven panelists, and no compression tests by Instron were run.
RESULTS AND DISCUSSION Experiment A. Table 1 summarizes the effects of phosphate-salt treatments prior to and after cooking on water absorption, cooked yields, and rehydration capacity of the freezedried products. Water absorption of chicken breasts soaked in a solution of polyphosphates (Kena) with sodium chloride was more than twice that of breasts' soaked in water and cooked yield (based on original raw unsoaked weight) was increased 13% by the polyphosphate-salt treatment. Polyphosphate-salt treatment of sub-lots l b and 2b increased yield only about 5%. The final rehydrated yields ranged from 67% for the water-air control to 76% for the twice-soaked (salts-salts) sub-lot. These differences corresponded to 4% more moisture in the salts-salts rehydrated product than in the water-air control, i.e., 68.7% versus 64.5% (as calculated from the rehydration ratios and the moisture contents of the freeze-dried products). Hinnergardt et al. (1975) obtained a 6% difference in moisture content by phosphate-salt
TABLE 3.—Sensory scores of rehydrated freeze-dried meat. Experiment A Mean scores* Sublot la lb 2a 2b
Treatment
Juiciness
Tenderness
Saltiness
Water/air Water/salts** Salts/air Salts/salts
2.80 a 3.93°= 3.70b 4.47 c
2.48 a 4.42 c 3.73b 4.92 d
1.87 a 3.70b 3.28b 4.53=
'Means for 10 panelists and 6 replications, 1 = very dry or tough or bland; 6 = very juicy or tender or salty. **4%NaCl, 3% Kena. a,b,cr Different superscripts in columns indicate significant difference at 5% level.
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taining 1% sodium chloride to an internal meat temperature of 77 C. The cooked meat was drained, chilled t o —3 C overnight, machinediced to 1.27 X 1.27 X .95 cm size, frozen on trays in the available —34 C air blast, and freeze-dried in a Vac-U-Dyne pilot freeze-dryer (Model VPFD-CX). Pressure attained by vacuum pump was 500 microns; condenser temperature, about —45 C; and platen temperature, about 37 C. The reduction of platen temperature from that used in Experiment A was made to minimize heat damage. Freeze-drying required about 48 hr. Vacuum was released with nitrogen, and the dried product stored in desiccators under nitrogen at —34 C prior to evaluation.
3.20*
100.0 103.1 (2% NaCl) 72.7 71.0
Lot 2
3.35 b
100.0 120.6 (3% 93.8 77.6
Lot 3
Weight (% raw) after treat
(2% NaCl) 3.6° .65° .60*
(Water)
2.7 a .08 a .59 a
Means for duplicate determinations on dry basis; standard errors, from pooled variance, were .1 for ash, .08 fo ent superscripts within rows indicate significant difference at 5% level.
%Ash % Chloride, as NaCl % Phosphorus
Lot 2
Lot 1
TABLE 5.—Minerals in freeze-dried meat. Experiment B
•Rehydrated weight divided by freeze-dried weight. Standard error .04. Different superscripts indicate significant dif
3.17 a
100.0 99.0 (water) 68.6 68.5
None (raw) 6 hr in water or solution Cooking Freeze-drying and rehydration
Rehydration ratio*
Lot 1
of phospbate-salt treatments on water absorption, cooked yields, and r of freeze-dried chicken. Experiment B
Treatment
TABLE 4.—Effects
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TABLE 6.—Sensory scores of rehydrated freeze-dried meat. Experiment B Mean scores* Lot
Treatment
Juiciness
Tenderness
Saltiness
Water 2% NaCl 3% Kena 2% NaCl, 3% Kena
2.46 a 2.54a 4.1lb 4.32b
2.64a 2.86a 4.64b 4.68b
2.36 a 2.82 a b 3.29b 4.04=
*Mean for four replications, 7 panelists. 1 = Very dry or tough or bland; 6 = very juicy or tender or salty. a,b,c,Different superscripts in columns indicate significant difference at 5% level.
hydrated freeze-dried products, yield of the salt-Kena lot was 17% greater than that of the control. The rehydration ratio was significantly higher in lots 3 and 4 (Kena) than in lots 1 and 2, for tests with 20-g portions. Similar results were obtained with 100-g portions. Table 5 summarizes the data on mineral content. If we assume that the phosphate in the ash is in the ortho form, i.e., with phosphorus content around 22%, then increases in ash content can be accounted for essentially by combined increases in chloride (NaCl) and phosphate (Na 2 HP0 4 ). Sensory data (Table 6) showed that lots 3 and 4 were significantly more juicy and tender than 1 and 2. The saltiness of the salt plus Kena-treated lot was more intense than that of all others, and Kena alone significantly increased saltiness. However, all four lots received a small, probably slight, increment of saltiness from the cooking water which contained 1% sodium chloride. Results of these tests indicate that the quality of freeze-dried cooked chicken would be improved significantly by polyphosphates (Kena) and slightly more by both Kena and sodium chloride. There does not appear to be any advantage in applying polyphosphates before cooking in the early post mortem period compared to applying after cooking. Increases in rehydration capacity due to polyphosphate treatment were small but significant. While applications in these tests were made by soaking, commercial incorporation of polyphosphates and salt might better be made by injection. REFERENCES Association of Official Agricultural Chemists. 1975. Page 417—418 in Official methods of analysis of
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treatment in freeze drying beef, i.e., 56% versus 50%. Our values for the rehydration ratio, determined with five 20-g portions, were all significantly different from one another except for l b and 2a. Rehydration ratios obtained from the 100-g portions used in the sensory tests were lower than those in Table 1, ranging from 2.56 to 2.81; but the order of the sub-lots with respect to the amounts of water they took up was the same for both portion sizes. Probably there was greater loss of fine material through the sieves when the larger portions were handled. Table 2 provides some mineral contents of the four sub-lots. Increases in ash content corresponded roughly to increases in chloride and phosphorus. On a rehydrated weight basis, the salts-salts samples had .45% equivalent Kena (of 25.7% phosphorus content), based on the increment of phosphorus over the water-air control. On rehydrated weight basis, the salts-salts samples contained 1.3% more sodium chloride than the water-air control. The sensory panel data (Table 3) showed consistent increases in juiciness, tenderness, and saltiness in the order of sub-lots la, 2a, l b , and 2b; but not all differences were statistically significant at the 5% level. Compression tests on the rehydrated samples showed about 5% less liquid loss from the three Kena-treated sub-lots than from the water-air control (20% vs 25%). Experiment B. Table 4 summarizes the effects of polyphosphate and salt treatments on water absorption, cooked yields, and rehydration capacity of the freeze-dried products. The substantial gains in water absorption due to Kena were reflected in even larger gains, percentage-wise, in cooked yield. In the final re-
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